TY - JOUR
TI - Cross and clover shaped orifice jets analysis at low Reynolds number
AU - Meslem Amina
AU - Nastase Ilinca
JN - Thermal Science
PY - 2015
VL - 19
IS - 6
SP - 2139
EP - 2150
PT - Article
AB - The jet coming from a cross-shaped orifice with an open center has been shown  in the past, to provide substantial increase in the near field convective  transport-mixing, in comparison to a classical round orifice jet. Detailed  information has been reported in previous works on the role played in the jet  mixing enhancement by the crow of vortices composed of counter-rotating pairs  of secondary streamwise structures which are developing in orifice’s troughs.  A trough in the cross-shaped jet generates a local shear like the one  generated by a triangular tab in a square jet. In the present study we are  interested by the modification of local shears in the troughs of the  cross-shaped jet, when orifice geometry is modified, such as the center of  the orifice becomes closed, leading to a clover-shaped orifice. The general  motivation is to understand the effect of using a set of combination of  longitudinal structures, themselves produced by the superposition of local  shear regions, in mixing performance of a cross jet. It is shown that lower  entrainment rates in the clover jet is a results of a additional internal  crown of vortices which opposes the external one due to inner shears  generated by closing the center of the orifice.